Vinylene carbonate, an unsaturated, cyclic 1,2-substituted ethylene derivative of the formula, ##STR1## was first prepared and polymerized by M. S. Newman and R. W. Addor (J. Am. Chem. Soc. 75, 1263 (1953) and J. Am. Chem. Soc. 77, 3789 (1955)). Poly(vinylene carbonate) is readily hydrolyzed in basic and acidic media to produce poly(hydroxymethylene) in the form of intractible white powder. Poly(hydroxymethylene) is composed of recurring units of the formula ##STR2##
N. D. Fields and J. R. Schaefgen investigated properties of poly(hydroxymethylene) and reported that poly(hydroxymethylene) obtained by hydrolysis of poly(vinylene carbonate) with strong base or aqueous ammonia is a white powdery material soluble only in 30 percent aqueous sodium hydroxide and in sulfuric acid. They found that their high molecular weight polymer was not dissolved but only swollen by hot dimethyl sulfoxide and molten urea. Since the polymer was infusible and could not be fabricated into fibers and films using conventional methods, they made poly(hydroxymethylene) films for determination of mechanical properties of the polymer by first preparing a film of poly(vinylene carbonate) and then hydrolyzing the poly(vinylene carbonate) film to obtain a film of poly(hydroxymethylene) (J. Polymer Sci. 58, 533 (1962)).
Copolymers of vinylene carbonate with ethylenically unsaturated comonomers have, for example, been disclosed in U.S. Pat. No. 2,722,525 to Price et al. and U.S. Pat. Nos. 2,847,398 and 2,847,401, both to Gluesensamp et al. Such vinylene carbonate copolymers have been hydrolyzed to form the corresponding hydroxymethylene copolymers.
Poly(hydroxymethylene) and copolymers are obtained by processes which involve the polymerization of vinylene carbonate followed by hydrolysis of the poly(vinylene carbonate). It has been found that this polymer is essentially insoluble in all common solvents and solvent systems which are used for polymers and which are characterized by extraordinary solubility properties.
Huffman et al. in U.S. Pat. No. 3,344,102 have disclosed solutions of poly(hydroxymethylene) and of copolymers of hydroxymethylene with certain ethylenically unsaturated comonomers, including vinyl acetate, vinyl chloride, vinyl fluoride, acrylonitrile and acrylamide, in aqueous solution of zinc chloride, which solutions, they stated, are useful for fiber and film formation.
Huffman et al. further disclose that solutions of dimethyl sulfoxide with zinc chloride and of dimethyl acetamide with lithium chloride do not disolve poly(hydroxymethylene).
It has been reported that poly(hydroxymethylene) is soluble in systems such as hydrazine, concentrated alkali, concentrated zinc chloride solution and fused urea. It was reported to be insoluble in solutions such as zinc chloride in dimethyl sulfoxide, alcohols, glycols, dimethylene acetamide and also in a solution of lithium chloride in dimethyl acetamide.
Duvakina et al. in Zhurnal Prikladnoi Khimii, Vol. 40, January 1967, page 136 reports the preparation of copolymers of vinylene carbonate with vinyl acetate and Klubikova et al. in Zhurnal Priklodnoi Khimii, Vol. 38, 1965, page 1188-1191 report on the copolymerization of vinylene carbonate and vinyl acetate in the presence of redox systems. Furthermore, N. G. Schnautz in Journal of Polymer Science, Vol. 14, page 1045 [1976] reports on the radiation copolymerization of vinylene carbonate with isobutyl vinyl ether. While the prior art has addressed itself to the problem of bringing poly(hydroxymethylene) into solution there is still need for a good solvent of this polymer which would enable the fabrication of fibers made from polyhydroxymethylene which is expected to have properties similar to those of cotton.
Poly(hydroxymethylene) and copolymers of hydroxymethyllene containing up to about 30 mol percent of ethylenically unsaturated comonomers may be prepared by polymerizing vinylene carbonate singly or together with ethylenically unsaturated comonomers, by known methods in bulk, solution, suspension or dispersion, under atmospheric or superatmospheric pressure, in the presence of a free radical generating initiator to obtain as precursor polymer poly(vinylene carbonate) or copolymers of vinylene carbonate with ethylenically unsaturated comonomers, followed by hydrolysis of the precursor polymer to obtain poly(hydroxymethylene) or copolymers of hydroxymethylene with ethylenically unsaturated comonomers. Preparation of the poly(vinylene carbonate) and copolymers of vinylene carbonate with ethylenically unsaturated comonomers has, for example, been described in the references discussed above under Background of the Invention.
Ethylenically unsaturated copolymers with vinylene carbonate believed to be useful in the present invention have, for example, been described by Price et al. in U.S. Pat. No. 2,722,525 the disclosure whereof is incorporated herein by reference.